PROJECT SUMMARY Sepsis is one of the most common life-threatening illness, leading to high mortality rates in both developed and developing countries.1 In the US alone, sepsis afflicted 1 to 3 million patients, caused 250,000 to 375,000 deaths in 2009,2 and accounted for $20.3 billion of US hospital costs in 2011.3 Besides the complex, redundant and often variable immunological responses,4 sepsis is always characterized by vasodilation and vascular leakage (VL),5-7 two constant, independent and complementary downstream cardiovascular pathogenic features directly responsible for decreased organ perfusion, tissue edema, organ dysfunction, multiple organ failure, and death. Today, sepsis patients are initially treated with antibiotics and given resuscitation fluids to maintain arterial blood pressure (ABP). Fluids are however purely symptomatic and do not address the root causes for decreased organ perfusion and function. Most concerning, they often lead to fluid overload,8 thereby further increasing tissue edema, organ failure, and mortality.9-12 Once fluids are no longer able to sustain ABP, patients progress to septic shock and are treated with marginally efficacious off-label vasopressors.13 This program aims to develop a new drug with a dual mechanism of action for sepsis capable to concomitantly block vasodilation and VL while eliminating resuscitation fluids. The two molecular targets selected herein to respectively block vasodilation and VL are supported by strong scientific and clinical evidence derived in part from previous team contributions to the field. The chemical feasibility to drug these two targets has already previously been established by the team, and active pharmacophores for the two targets are already available. The program will consist in 1st) demonstrating feasibility to create bi-functional molecules by covalently linking target 1 and 2 active pharmacophores (Aim 1); 2nd) demonstrating that bi-functional molecules retain activity at the two molecular targets (Aim 2); and 3rd) establishing that bi-functional molecules concomitantly block vasodilation and VL in a surrogate pharmacological model of sepsis (Aim 3). IMPACT &